Conventionally, so-called integrated coal gasification combined cycle power plants (IGCC) have been developed and put into practical use with the goal of improving the power generation efficiency of coal-fired power plants. Such an integrated coal gasification combined cycle power plant (hereinafter, referred to as an “IGCC”) includes a gas turbine generator that uses coal gas obtained by gasifying coal as a fuel, to operate and generate power, and a steam turbine generator that uses the steam obtained by recovering heat from high-temperature combustion exhaust gas discharged from the gas turbine using an exhaust heat recovery boiler, to operate and generate power.
In such an IGCC, the fuel supply to the gasifier that generates the coal gas is performed by transporting a solid fuel that has been pulverized into particles to a burner by using gas flow of nitrogen, carbon dioxide, air, or the like as a carrier gas, and jetting the solid fuel from the burner into the gasifier. On the other hand, a high-pressure operation in which the internal pressure in the gasifier is set high is performed, in view of the configuration of the system and the reactions inside the gasifier.
In order to perform such a high-pressure operation, the gasifier that is operated at a high pressure is formed as a pressure vessel, and a burner that penetrates through the wall surface of this pressure vessel houses a solid fuel (pulverized coal, petroleum coke, or the like) and a gasifying agent (air, oxygen, water steam, or the like) in the same pipe.
FIG. 10 shows a conventional structure in which the burner section of a gasifier is enlarged. In the structure, a burner for highly caking coal (hereinafter referred to as a “burner”) 12′ is attached penetrating through a surrounding wall (furnace wall) 11 of a gasifier 10 that is formed as a pressure vessel. The burner 12′ has a double pipe structure in which a solid fuel channel 13 on the inner side and a gasifying agent channel 14 on the outer side are arranged concentrically.
The solid fuel channel 13 is connected via a fuel supply line 16 with a high-pressure fuel supply unit 15 that supplies a solid fuel that has been pulverized into particles. Also, a carrier gas whose flow rate is controlled by a flow rate control unit (not shown) is supplied to the high-pressure fuel supply unit 15. Accordingly, the solid fuel channel 13 supplies the solid fuel, which is adjusted to the desired supply rate by the high-pressure fuel supply unit 15, into the gasifier 10, using the carrier gas, which is adjusted to the desired flow rate by the flow rate control unit. That is, the particulate solid fuel is transported by the carrier gas flow, and supplied into the gasifier 10.
The gasifying agent channel 14 is connected with a gasifying agent supply line 17 that supplies a gasifying agent, and supplies the gasifying agent, which is adjusted to the desired supply rate by a flow rate control unit (not shown), into the gasifier 10.
Thus, by supplying the solid fuel, the carrier gas and the gasifying agent into the gasifier 10, the solid fuel that has undergone a predetermined treatment in the gasifier 10 is gasified, and supplied to a gas cleanup facility in a subsequent step.
As another conventional technology, in a pulverized raw material gasification apparatus of the entrained flow-type that uses a pulverized carbon raw material such as coal as a gasification raw material, in addition to using a carrier gas, such as nitrogen gas, for the gasification raw material and an oxidizing agent such as oxygen or air, and gasifies the raw material at a temperature of at least the melting point of the ashes of the pulverized carbon raw material, it is known to provide a gas spouting nozzle upstream of an area near an exit portion where the carrier line of the gasification raw material is supplied into the gasification apparatus, in order to spout a gas such as nitrogen gas, carbon dioxide gas, or an inert gas toward the exit portion of the carrier line, and cause that gas to mix with the gasification raw material. This gas spouting nozzle blows away slag or the like adhering to the exit portion of the carrier line of the gasification raw material, and is considered to be capable of constantly maintaining a state where no matter is adhering to the burner exit portion (for example, see Patent Citation 1).
In addition, a technology has been disclosed by which an auxiliary mixing nozzle that blows, as gas flow, compressed air supplied from a part of a secondary fuel air or from the outside of a wind box is provided in a pulverized solid fuel combustion apparatus that burns a mixture of a solid fuel such as pulverized coal and a gas such as air as a fuel, thereby preventing the erosion of a fuel-air mixture nozzle and the adhesion and deposition of the fuel (for example, see Patent Citation 2).
Patent Citation 1: Japanese Examined Patent Application, Publication No. Hei 08-003361 (see FIG. 1)
Patent Citation 2: The Publication of Japanese Patent No. 3790489